Drought and rising sea levels, the impacts of climate change that will most affect the Mediterranean basin

Human-induced climate change is causing dangerous and widespread disruption to nature and affecting the lives of billions of people around the world. People and ecosystems with the least capacity to cope are already the hardest hit, says the scientific community in the latest report of the Intergovernmental Panel on Climate Change (IPCC), released today. The scientific community warns that the world is facing multiple climate risks over the next two decades, which in the Mediterranean have already resulted in a warming of 1.5°C (above the global average of 1.1°C).

If emissions are not reduced in the coming decades and the warming level set in the Paris Agreement (1.5°C) is temporarily exceeded, serious impacts will occur, some of which will be irreversible. The new report, prepared by Working Group II of the IPCC, has focused on the analysis of the impact, adaptation and vulnerability of natural ecosystems and socio-economic systems to climate change, as well as analysis of the best strategies to reduce its impact at different scales. This international team of experts includes Jofre Carnicer, Professor of Ecology at the Faculty of Biology at the University of Barcelona and researcher at the Centre for Ecological Research and Forestry Applications (CREAF), who is the only expert in Catalonia - and one of the few researchers in the whole of Spain - to have taken part in this report. The document was approved on Sunday 27 February 2022 by the 195 member governments of the IPCC in a virtual approval session that lasted two weeks, from 14 February until yesterday. The final report is the second instalment of the IPCC's Sixth Assessment Report (AR6), which will be completed this year.

According to the scientific community, between 3.3 and 3.6 billion people live in a context of high vulnerability to climate change, almost half of humanity. Globally, the most vulnerable areas are Central Africa, Southeast Asia and Central America, while in the case of the European continent, the most threatened region is the Mediterranean area. In this respect, the new report is blunt: to avoid increasing loss of life, biodiversity and infrastructure, ambitious and accelerated action is needed to mitigate and adapt to climate change. Despite steady progress in local experiences on how to reduce the negative impacts of climate change in different sectors (adaptation), the report finds that there is still a gap between the total needs and the pioneering actions that are progressively being implemented. The impacts of climate change are greater among lower income populations, in certain geographical areas of the world that are more vulnerable, and are also modulated by age and gender. The report highlights that current economic development is unsustainable, and that it is essential to consider the inclusive participation of all social actors, and equity and climate justice, in order to develop transformative mitigation and adaptation actions towards a sustainable and climate-resilient development model.

"This report is a dire warning about the consequences of inaction," warns IPCC chairHoesung Lee. "It shows that climate change is a serious and growing threat to our well-being and to maintaining a healthy planet. Our actions today will determine how people adapt and how nature responds to the growing climate risks.

This report is a dire warning about the consequences of inaction.

Hoesung Lee, chariman of the IPCC

"The environmental cost of inaction is very high, and the report concludes that action is needed before the window of opportunity we have, which is only two to three decades, closes. Every action is relevant, whether at the governmental and international level, in industries and sectoral activities, or in changes to citizens' lifestyles, and these actions can progressively contribute to reducing warming and impacts in the coming decades and for generations to come. The report stresses the need for urgent, profound and transformational changes in all sectors of society and, most especially, in all economic activities that generate emissions. The costs of adapting to the impacts of climate change will be much higher if we do not implement drastic and decisive emission reductions over the next two decades that put us on a warming trajectory below 2°C," warns Jofre Carnicer, IPCC lead author for the European and Mediterranean chapters. Jofre Carnicer, lead IPCC author on the European and Mediterranean chapters.

Biodiversity on the edge

Increasing heat waves, droughts and floods are already exceeding the tolerance thresholds of many plants and animals, leading to local extinctions of populations of some temperature-sensitive or low-mobility species. 

The summary of the IPCC report states that human and ecosystem vulnerability are interdependent. It therefore focuses on the current and future effects of climate change on biodiversity. More than 40,000 studies covering marine and terrestrial systems around the globe have been used. The science says that increased heat waves, droughts and floods are already exceeding the tolerance thresholds of many plants and animals, causing local extinctions of populations of some temperature-sensitive or low-mobility species, such as endemic or more specialist species, or mass mortalities of species in habitats more vulnerable to heat stress, such as seagrass meadows or coral reefs. The report is supported by scientific studies that warn that more than 50% of the planet's species have moved in recent years to more northerly latitudes, or to higher altitudes, to escape rising temperatures.

The risk of extinction of more than 100,000 species for which scientific documentation exists has also been analysed. The results are worrying, "we can see that in warming trajectories above 1.5 ºC, that is, without a drastic reduction in emissions in the next two decades, the risk of extinction increases in many taxonomic groups, often by more than 10% of the species", warns Jofre Carnicer. The report does not give results or species information at the local level, because each species has a unique ecology and each pattern is extremely complex, but it does highlight the first documented extinction of a mammal species. This is the mosaic-tailed mouse (Melomys rubicola), native to a low-lying tropical islet (Cai) off Papua New Guinea, which has become extinct after its habitat was drastically reduced by extreme climatic impacts and rising sea levels.

Adaptation measures to maintain biodiversity and whose services we absolutely depend on as a society include the restoration of ecosystems, the use of nature-based solutions and the increase of protected land.

Adaptation measures to maintain biodiversity and whose services we absolutely depend on as a society include the restoration of ecosystems, the use of nature-based solutions and the increase of protected land. "The planet's natural areas need to be protected more consistently because we are so dependent on ecosystem services to maintain climate security on the planet. Oceans and forests absorb 50% of our greenhouse gas emissions and contribute to regulating global temperature. The report documents that an increase in climate impacts can cause declines in the efficiency of global CO₂ absorption by ecosystems and thus positively feedback warming," warns Jofre Carnicer. To this end, the report advocates moving from 16% of the world's protected areas, a figure agreed in the World Biodiversity Convention, to 30% or even 50% by 2030. "The solutions based on protecting nature or restoring it are important, but they must necessarily be accompanied first and foremost by drastic reductions in gas emissions in multiple sectors over the next two decades," says Carnicer.

An asymmetric Mediterranean at risk

The Mediterranean is warming faster than most areas of the world. In this environment, the temperature has already risen by 1.5°C, while the global average remains at around 1.1°C. There is consensus that drought will be a major risk in the Mediterranean. In this sense, predictions point to a considerable increase in droughts: for every degree increase in temperature, we will see a 4% reduction in rainfall, so that reductions of between 5% and 20% are predicted, depending on our capacity to reduce emissions.

In the Mediterranean, the use of water in agriculture should be a key point to try to adapt to this drought and rising temperatures. At the same time, other forms of agriculture that are more efficient and better at maintaining soil moisture, such as regenerative agriculture that maintains a more fertile soil rich in organic matter, should be promoted.

Moreover, vulnerability to climate change in the Mediterranean basin is highly asymmetric. The report reviews the Sustainable Development Goals in this area and shows that the indicators are extremely different between the southern and northern shores of the Mediterranean basin. The southern shore has lower rates of poverty, food security, access to renewable energy, water, education and health. This exposes people in this area even more to the effects of climate change, as they have fewer resources to adapt to future impacts, for example. "A very clear example of this increased vulnerability to climate change on the southern shore of the Mediterranean is the rise in sea level in Egypt, a country of 103 million people. In the Nile Delta alone, it is expected that more than 6.3 million people could be seriously affected if sea levels rise above 80 cm, a scenario envisaged with today's greenhouse gas emission trends".

Food security

In Europe, agriculture will be a major focus of climate change impacts and adaptations. Science already shows that European crop losses due to drought have tripled in the last 50 years. Worldwide, production declines of up to 5% have also been seen in the three main crops (maize, wheat and rice). Looking ahead, productivity reductions of up to 17% are expected in the Mediterranean region under worst-case scenarios. Moreover, globally, it is estimated that around 10% of arable land will not be able to be used for agriculture due to climate change under high warming scenarios. In addition, farm workers could be subjected to 250 very hot days per year.

Science already shows that over the last 50 years, European crop losses due to drought have tripled. 

Although adaptation measures are already being taken in agriculture, such as changes in crop timing, shifting crop areas to higher elevations, or using species that are more resistant to salinity or water stress, the report documents that in high warming scenarios (>2°C) some adaptation measures may no longer be effective and may not be able to maintain current food production.

Climate-resilient development

The report thus highlights the need for fair and inclusive governance schemes, where adaptation measures are taken including the voice of all stakeholders, facilitating co-creation of solutions at different levels. 

The current report recognises that current human development is neither sustainable nor resilient to climate change. In this context, the report highlights the need for transformative actions that both drastically mitigate the emissions and effects of climate change and enable adaptation of land and people, with a particular emphasis on the need for inclusive and equitable choices. The report thus highlights the need for fair and inclusive governance schemes, where adaptation measures are taken including the voice of all actors, facilitating co-creation of solutions at different levels. Thus, for example, the knowledge of local and indigenous populations is taken into account, as well as more scientific knowledge. Finally, the scientific community stresses in its report the need for international cooperation and collaboration of governments at all levels with communities, socially disadvantaged groups, civil society, educational bodies, scientific and other institutions, the media, and investors and businesses to facilitate more sustainable and climate-resilient developments.

IPCC: international science for the benefit of environmental policies

IPCC reports provide governments with a set of data of the highest scientific interest that they can use to shape climate policy. They are also a key contribution to the international negotiations to address climate change under the United Nations Framework Convention on Climate Change (UNFCCC).

Specifically, the IPCC comprises three working groups: Working Group I, which analyses the physical basis of climate change; Working Group II, which studies impacts, adaptation and vulnerability; and Working Group III, which focuses on climate change mitigation. Now, the new WGI report expands on the climate change knowledge framework released by the WGI in August 2021 as part of the IPCC's Sixth Assessment Report (AR6).

To produce the new report, an international scientific team of nearly 200 experts - appointed by each country's government - have worked in a coordinated manner over the past seven years to compile the maximum amount of scientific information - more than 40,000 publications - on the issue of climate change. Subsequently, all the knowledge acquired has been reviewed at different stages by leading experts from all over the world, as well as by governmental interlocutors who develop public policies related to climate change. inally, the report summarising the most important findings is presented publicly and openly to the whole of society.